Install an adblocker on Firefox - uBlock Origin
uBlock Origin is an independant and open-source ad-blocker relying on a currated list of servers. It prevents your browser from connecting to these servers to serve you ads. We recommand it over AdBlock Plus which allows certain ads according to its "Acceptable Ads program".
Click "Add to Firefox"
uBlock will then be installed. No other configuration is required, You should now have the uBlock Origin icon in the top right corner of you browser. Clicking on it will let you see how many ads have been blocked and temporary disable it if you cannot load a specific page or if you want to enable ads on a specific website.